The present invention provides a plasticizer for polymer resins, and more particularly, a phthalate-free plasticizer for polymer resins comprising a mixture of different triesters of glycerin, and a method of making the same.
Plasticizers are compounds or mixtures of compounds that are added to polymer resins to impart softness and flexibility. Phthalic acid diesters, which are also called phthalates, are the primary plasticizers for most flexible polymer products, especially polymer products formed from polyvinyl chloride (PVC) and other vinyl polymers. Examples of common phthalate plasticizers include, for example, di-isononyl phthalate (DINP), diallyl phthalate (DAP), and di-2-ethylhexyl-phthalate (DEHP).
Although phthalate plasticizers have been tested for more than 40 years and are among the most studied and best understood compounds in the world from a health and environmental perspective, phthalate plasticizers have recently come under intense scrutiny by public interest groups that are concerned about the potential of adverse health effects in children exposed to these chemicals. Consequently, there is a demand for phthalate-free plasticizers that provide the same properties when added to polymer resins such as, for example, vinyl polymers, rubbers, polyurethanes, and acrylics.
The present invention provides a phthalate-free plasticizer for polymer resins and a method of making the same. A phthalate-free plasticizer according to the present invention comprises a mixture of different triesters of glycerin, at least one of which meets the formula:
CH2(OOR1)CH(OOR2)CH2(OOR3)
wherein at least two of R1, R2, and R3 are different alkyl or aryl groups. In a preferred embodiment, R1, R2, and R3 each contain up to about 11 carbon atoms, and more preferably from about 2 to about 11 carbon atoms each.
The phthalate-free plasticizer according to the present invention is compatible with a wide variety of polymers including vinyl polymers, rubbers, polyurethanes, and acrylics. In addition, the phthalate-free plasticizer according to the invention has superb thermostability and low volatility.
The phthalate-free plasticizer according to the invention can be made by heating glycerin and a mixture of at least two different acids in the presence of a catalyst to form a mixture of different triesters of glycerin, at least one of which meets the formula:
CH2(OOR1)CH(OOR2)CH2(OOR3)
wherein at least two of R1, R2, and R3 are different alkyl or aryl groups. In a preferred embodiment, the glycerin and mixture of acids are heated while under a partial vacuum to assist in the removal of water.
The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed.